Unloader for gas compressors



Nov. 21, 1933. A E SCHNElDER 1,936,411

UNLOADER FOR GAS COMPRESSORS Filed Feb. ll, 1932 2 Sheets-Sheetl l lh 30 'I A# s Z4 /d 9 D 35 25 Z0 .37 Il I Z5 l 33 32 j? d a 3f 20 /z 5 4 li Z 42 a A l Y. /4 33 y 4/ 45 y /3 i 7 /7 gol 1 i///f/j/j/ ,i fwri; t @I (//g 4f 57 u /Y 4 115:' l Y l l I I 5g g l1 5 I' 57 i /0 l 57 7 5 A I ff N 58 l If n 's g; J i

IN VEN TOR.

v n I W7 l 'M/ ATTORNEY.

Nov. 21, 1933. A. E. SCHNEIDER 1,936,411

UNLOADER FOR GAS COMPRESSORS Filed Feb, 11, 1932 2 sheets-sheet 2 M 427 ffy/ I NVEN TOR. 52 Awe/ff. Jaffe/ae/ A TTORNE Y.

Patented Nov. 21, 1933 ,Y

UNLOADER FOR GAS CQMPRESSORS Albert E. Schneider, Carter Lake, Iowa, assigner to Baker Ice Machine Co. inc., Omaha, Nebr., a corporation of Nebraska Application February 11, 1932. SerialNo. 592,270 8 Claims. (Cl. 230-24) My IlVcntOn relates t an unloader Ol gas space adjacent the opposite side Wall to accommocompressors and more particularly to mechanism date unloading mechanism installed through an of that character for use in mechanical refrigera.- elongated opening l2 provided in the partition 6, tion apparatus operated by electrical motors as later described. Each cylinder may comprise b' laVHg lelVelY 10W DOWBI COIISUIHDOH; the a sleeve 13 having a peripheral flange 14 for seat- 60 principal object of the invention being to utilize ing in a counter-bore ll5 of the opening in the the current surge incidental to initial and interupper partition and having a reduced skirt pormittent starting of the motor for controlling option 16 pressed into the opening in the lower pareration of the compressor suction Valves, thereby timori, The cylinders are. provided 'at a point 1o effecting temporary relief of the compressor load below the upper partition with arcuate-shaped e5 on the motor. auxiliary ports 1'7 opening to the low pressure In accomplishing this and Other Objects O the chamber, and with gas inlet channels 18 extendinvention, I have provided improved details of ing vertically from the upper faces of the anges structure, the preferred form of which is illus 14 to the ports vl7,`so that refrigerant may be tfaled 11 the aCCOmDaYlyng drawings, wherein: drawn from the low pressure chamber through 70 Fig. l S a pEISDSCtVe View Of a Teflgelatng the channels 18 upon the suction stroke of the apparatus equipped With my improved unloading compressor pistons, as well as directly through mechanism, parts 0f the SOY-113195501 Walls being the auxiliary ports when the pistons have reached broken away to illustrate the location and operathe ends of their suction strokes, and whereby 2o tion of the unloading mechanism. the refrigerant may be returned to the low pres- 75 Fig. 2 is a perspective view of the suction valves sure chamber upon actuation of the unloading illustrating related parts of the unloading mechmechanism, as later described. anism in spaced position, to better illustrate their Seated on the `upper partition 6 is a valve construction. plate 19 conforming to the shape of the cylinder Fig. 3 is a perspective View of one of the dshousing and provided 'with a longitudinal open- 80 Charge Valves and its Cageing 20 aligning with the opening Vl2 previously de- Eig. 4 is an enlarged sectional perspective View scribed, and with recesses 2l on its bottom face in of one of the suction valves. line with the channels 18 to prevent the plate from Fig. 5 is a vertical section of the compressor closing off passage of refrigerant to and from 3o head through one of the compression cylinders. said channels. 85

Fis. 6 is an enlarged vertical Section through The discharge valve plate is also provided conone of the cylinders showing the suction valve and centrically of each cylinder with a discharge port COlllOl Parts in llIllOaClng position. 22 communicating with a high compression cham- Fig. '7 is a similar view showing the parts as ber 23 provided in a cylinder head 24 that is they appear when the compressor is operating mounted on the upper face of the valve plate. 90 at normal speed. To prevent leakage, suitable gaskets 25 are in-` Fig. 8 is a circuit diagram including the motor sorted between the cylinder housing and the lower running and starting windings, the unloading face of the valve plate and between the upperV coil and the automatic switch for effecting energiface of the valve plate and the cylinder head. zation of the starting winding and the unloading The head and plate are retained by suitable stud 95 coil. bolts 26, as in standard compressor construction. Referring more in detail to the drawingsl- The low compression chamber is provided with 1 designates a reirigerating apparatus wherein a gas inlet port 27 communicating with a suction the condenser coil 2, compressor 3 and its operatline 28 that is connected to the refrigerant exing motor 4. are located relatively to each other pansion coil (not shown), and the high pressure 100 to form an enclosed self-contained unit. chamber is provided with a discharge port 29 The compressor illustrated includes a cylinder communicating with a high pressure line 30`c0nhousing 5 having its upper and lower ends closed nected with the condenser coil 2. by partition walls 6 and '7 to form a low pressure The discharge ports 22 are valved by disk type chamber 8. Provided in the partition walls are valves 3l that are retained in seating relation with 105 pairs of aligning circular openings 9 and l0 ford the upper face of the Valve plate by a valve cage ing seats for supporting upper and lower ends member 32 which preferably comprises a spring oi cylinders 11. metal leaf 33 fixed to a boss 3e located on the The openings 9 and 10 are preferably located plate at a point midway between the cylinders, Y close to a side Wall of the housing to provide a screw 35 being extended through an opening in 110 the leaf and threaded into the boss. The ends of the leaf extend over the discharge valves and are provided with a circular series of depending lugs 36 encircling the valve disks and having their ends engaging the valve plate to form cages in which the valves are reciprocably retained under control of spring-like tongues 37 stamped from the metal leaf.

The auxiliary ports 17 are valved by the compressor pistons 38 and the upper ends of the channels 18 are Valved by disk-shaped valves 39 seated in recesses 40 formed in the cylinder flanges 14 at the upper ends of the cylinders as best illustrated in Fig. 6.

The Valves 39 are normally urged to their seats by a leaf spring 41 having its intermediate portion anchored in a groove 42 formed in. the under face of the valve plate and extending longitudinally in line with the inlet valves. The free ends 43 of the spring are preferably bent downwardly to engage the upper face of the valves to retain them on their seats.

The motor 4, preferably of the split phase type, is directly connected to the operating shaft (not shown) of the compressor for actuating the pistons 38 whereby each piston on its suction stroke effects lifting of its related suction valve 39 to draw a charge through the channels 18 into the cylinder. When the piston has reached the limit of its suction stroke, the auxiliary port 17 is uncovered to allow additional gas. to enter the cylinder to assure the complete filling thereof. When the piston begins its compression stroke, the port 17 is closed thereby and the suction valve is closed by the compression of the gas, supplemented by the pressure of the spring 41, so that the trapped gas is discharged through the port 22, lifting the valve 31 against tension of the tongues 37 and gas pressure in the high pressure chamber.

In order that a compressor of the type illustrated may be actuated by a motor of the split phase type having relatively low current consumption, it is necessary to initially relieve the motor from the load of compression until the motor attains its proper working speed. To effect this result I provide for automatically lifting the suction valves from their seats so that the gas is simply drawn into the cylinders and returned to the low pressure chamber until the motor has attained its proper working speed, as

now described.

Reciprocably supported in the channels 18 are triangular-shaped pins 44 having their upper ends adapted to bear against the under face of the suction valves and their lower ends are supported on lever arms 45 projecting from a rock shaft 46. y

The rock shaft 46 is pivotally mounted in the low pressure chamber and comprises a cylindrical rod 47 having reduced pivot ends 48and 49 which are respectively supported in a socket 50 formed in a wall of the cylinderhousing and in a socket 51 provided in the end of a screw 52 that is threaded through the opposite wall of the housing as illustrated in Fig. 1. The shaft is thus supported in position so that the lever arms extend into the auxiliary ports 17 to lift the pins when the shaft is rocked on Yits pivots.

In order to effect operation of the rock shaft, it is provided intermediate the lever arms 45 with an oppositely directed lever` arm 53 forming an armature of an electro-magnet 54 now described.

The electro-magnet 54 includes a spool 55 having a laminated core 56 supported on bracket arms 57 that are attached to bosses'58 extending upwardly from the lower partition 7 of the cylinder housing, the brackets being secured to the bosses by suitable fastening devices 59. The brackets preferably extend upwardly within the spool along the sides of the core 56 and are bent outwardly to lie flat against the upper face of the spool as illustrated in Fig. 1, to retain the spool and form an abutment 60 for a leaf spring 6l. The flat leaf spring 61 is attached to the rock shaft and extendsy parallel with the armature lever arm 53 to normally retain the lever arms 45 in retracted position, so that the lever arms 45 will allow the suctionV valves to seat and perform their normal function of trapping the refrigerant charges in the cylinders on the compression strokes of the pistons. .In order to energize the electro-magnet, it is connected into the motor circuit as now described.

Referring to the circuit diagram illustrated in Fig. 8, 62 and 63 represent the lead wires of an electric circuit to which is connected the motor running winding 64 of the split phase motor. Also connected in the circuit in series with the motor running coil is a solenoid 65 for actuating a switch 66 that connects the motor starting winding 67 into the circuit. Also connected in circuit in series with the starting winding of the motor and adapted to be energized simultaneously therewith is the unloading coil 54 previously described, and a relay shunt coil 68.

A refrigerating unit constructed and equipped with an unloading device as described, and associated with a refrigerator in active use, operates as follows:

Assuming that the temperature in the refrigerator box is high, the master control switch associated therewith will act to close the circuit to the running winding 64 of the motor. Upon initial closure of the circuit a surge of current is effected through the line which is sufficient to energize the solenoid winding 65 of the switch 66 to close the circuit through the motor starting winding 67 and the winding of the unloading magnet 54.

Energization of the unloading magnet draws the armature arm 530i the rocker shaft 46 toward the core 56 to effect partial rotation of the shaft and lifting of the pins 44 to unseat the suction valves 39. The motor, therefore, is free of the compression load of the compressor, since the pistons, upon drawing refrigerant into the cylinders, return it through the open suction valves to the low compression chamber and no compression is effected. This condition is maintained in the compressor until the motor attains it's'normal working speed, or until the current consumption has dropped below the amount necessary to'energize the solenoid switch winding 65. When this occurs, the armature lever arm is released to permit the spring 6l to return the rock shaft toY normal position and allow seating of the suction valves.

The suction valves are then free to function according to the movements of the pistons, which, on their suction strokes, draw refrigerant from the low pressure chamber into the ports 17, channels 18, past the suction valves and intothe cylinders. At the end of the suction strokes, the

ports 17 are uncovered to assure complete filling l of the cylinders with refrigerant, in order that the compressor can operate at maximum efficiency. On the beginning of the compression strokes, the ports 17 are, of course, closed by the piston, at

which time the compression pressure closes the suction valves aided by the spring 41. The entrapped refrigerant is then discharged past the valves 39 into the high pressure chamber 23.

The compressor continues to operate to develop the required pressure diiference between the high and low pressure chambers, or until the master control switch has functioned to stop operation of the motor. Upon functioning of the master control switch the winding is again temporarily energized by the current surge to eifect operaton of the 'unloading mechanism, as previously described.

It is apparent that while there is an initial surge of current incidental to ciosing of the motor circuit, this surge never rises above the Vsafe capacity of the supply line fuses, since this surge functions to automatically relieve the motor cf its compression load, whereupon the surge begins to drop to that normally required to operate the motor at its rated speed, which, of course, reduces the current flow below the value required to energize the switch solenoid, and it is at this time that the compression load is applied to the motor. The current value therefore cannot possibly rise abcve that required to energize the solenoid switch winding which is below the safe capacity of the line.

Attention is directed to the fact that with the unloading mechanism functioning as described, the compressor is not required to begin operation against pressure in the high pressure chamber, because as soon as the suction valves are raised the pressures above the piston are equal to the pressures of the low pressure chamber. Such conditions often occur due to momentary failure of the current at a time the compressor is operating so that a pressure is partly built up in the high pressure side. Then before the partially built-up pressure has time to equalize with the low pressure side, the current again cornes on to start the motor.

Intermittent operation of the motor or even reduction of the motor speed,- due to line or other conditions, will cause operation of the unloading mechanism because reduction of speed will effect a current surge suficient to energize the switch solenoid 65.

What I claim and desire to secure by Letters Patent is:

l. In a compressor, a cylinder housing having a low pressure chamber, a compression cylinder in the housing having a suction port communieating with said chamber, a valve normally closing said port, a piston operable in the cylinder, a motor operably connected with the piston, a circuit for supplying current to the motor, means in the housing adapted to engage said valve to retain the valve in open position, and an electromagnet connectible in said circuit for actuating said valve-engaging means during excessive surges of current through the circuit.

l2. In a compressor, a housing having a lcw pressure chamber and a high pressure chamber, a cylinder in the housing, a piston operable in the cylinder for drawing gas from the low pressure chamber and discharging it into the high pressure chamber, valves controlling iiow from the low pressure chamber tc the cylinder and from the cylinder tc the high pressure chamber, a rocker shaft pivotally mounted in the housing, a lever arm on the rocker shaft, a valve-engaging pin supported by the iever and adapted to engage the vaive controlling now from the lcw pressure chamber to the cylinder, a motor for actuating the piston, a circuit supplying current to the motor, a. secondary circuit, a solenoid switch in the'rst named circuit for energizing the secondary circuit upon surges. of current through the irst named circuit, a-magnet in the secondary circuit, and means operableby the magnet for actuating the rocker shaft to retain said suction valve in non-functional position.

3. In a compressor, a cylinder housing having a low pressure chamber, a' cylinder in the housing having a suction port communicating with said chamber, a valve closing said port, a piston operable in the cylinder, a motor operably connected with 'the piston, a circuit for supplying current to the motor, means in the housing adapted to engage said valve to retain the suction valve in open position, and an electro-magnet operably ccnnectible in said -circuit oractuating said valve-engaging means during initial starting of the motor to relieve the motor of the starting torque of the compression load of the compressor.

4. In a compressor, a housing having a low pressure chamber and a high pressure chamber, a cylinder in the housing, a piston operable in the cylinder for drawing gas from the low pressure chamber and discharging it intol the high pressure chamber, valves'controlling flow from the low pressure chamber to the cylinder and from the cylinder toy the high pressure chamber, a motor for actuating the piston, a circuit supplying current to the motor, and means for rendering une of said suction valves ineffective including a secondary circuit, a solenoid switch in the first named circuit for rendering the second circuit effective upon surges of current through the iirst named circuit, an electro-magnet in the second named circuit, and means operable by the magnet for engaging said valve.

5. In combination with a compressor including low and high pressure chambers, a cylinder having a suction port communicating with the low pressure chamber and a discharge port ccmmunicating with the high pressure chamber, valves for said ports, a piston operable inthe cylinder, a motor for operating the piston, a circuit for supplying current to the motor, and means operable in response to initial surge of current in the circuit for opening the'suction valve and rendered inoperable in response to reduction in current flow to that required for operating the motor at its rated speed.

6. In combination with a compressor including low and high pressure chambers, a cylinder having a suction port communicating with the low pressure chamber and a discharge port communicating with the high pressure chamber, valves for said ports, a piston operable in the cylinder, a motor for operating the piston, a circuit for supplying current tcy the motor, and anv electro-magnet connected for energization by initial surge of current in the circuit and for deenergization in response to reduction of now of current in the circuit tc that required for operating the motor at running speed, the magnet having an armature operable toopen the inlet valve when the magnet is energized.

'7. In combination with a compressor including lcw and high pressure chambers, a cylinder having a discharge port communicating with the high pressure chamber and an Vinlet port communicating with the low pressure chamber, Valves for said ports, a piston in the cylinder, a motor for operating theY piston, a primary circuit for supplying current to the motor including a running winding, a starting winding having a normally open secondary circuit, an electro-magnet in circuit with the starting winding, means operable in'response to initial surge of current in the primary circuit for closing the secondary circuit and to reduction in flow of current in the primary circuit to that required for operating the motor at running speed for opening the secondary circuit, and means operable by the magnet for opening the inlet Valve and retaining the said Valve open during the starting phase.

8. In combination with a compressor including 10W and high pressure chambers, a. cylinder having a discharge port communicating with the high pressure chamber and an inlet port communicating With the low pressure chamber, valves for said ports, a piston in the cylinder, a motor for operating the piston, a primary circuit for supplying current to the motor including a runningwinding, a starting winding having a normally open secondary circuit, an electro-magnet in circuit with the starting Winding, meansoperable in response to initial surge of current in the primary circuit for closing the secondary circuit and to reduction in flow of current in the primary circuit to that required for operating the motor at running speed for opening the secondary circuit, means operable by the magnet for opening the inlet Valve and retaining the said valve open during the starting phase, and yielding means for returning said valve actuating means to permit the valve to close When the magnet is deenergized.

ALBERT E. SCHNEIDER. 

